The portable electronic device integrated with a digital camera is very popular at present, e.g. the cellphone with a photographing function. The portable electronic device features a small size, so it is important to manufacture the digital camera with a smaller size to be integrated with the portable electronic device. Besides, since most portable electronic devices are powered by batteries, whether the digital cameras integrated therewith are power-saving is also important.
For the digital camera, since the lens position thereof needs to be adjusted to obtain a proper focus, usually a focus adjusting module is equipped therewith. In the prior art, a DC or stepping motor is used with a transmission mechanism to adjust the position of the lens or photoactive element for focusing. However, the transmission mechanism complicates the assembly of the digital camera. Moreover, the mechanical noise will be generated since the transmission mechanism is driven by the motor.
For overcoming the above drawbacks, the magnetic force is currently used for focusing. A digital camera focusing mechanism is disclosed in Taiwan Patent No. 551,765, which changes the position of the photoactive element by the magnetic element, coil and elastic element for focusing. A current is provided in the coil to generate a magnetic field repelling the magnetic element, so that the photoactive element connected with the magnetic element moves due to the magnetic force. The elastic element enables the photoactive element to move continuously for achieving the continuous focusing. The displacement of the photoactive element is controlled by controlling the current provided in the coil.
A digital camera adjusting structure is disclosed in Japan Patent No. 2005-128405. A cylindrical structure is used to cover the lens module, and a yoke, magnet and coil are disposed on the cylindrical structure to surround the lens module. The lens module moves by means of the magnetic force generated by the magnet and coil for focusing.
Please refer to FIG. 1, which is an exploded view of the digital camera module in the prior art. A coil 111 is wrapped around a lens module 222. The coil 111 and the lens module 222 are placed in a holder 333, and a plurality of magnets 4 are disposed around the holder 333. The lens module 222 moves by means of the interaction between the magnetic force generated by the magnets 4 and that generated by the coil 111 after being electrified, thereby changing the position of the lens module 222 and thus the distance between the lens module 222 and the photoactive element for focusing.
Currently, the magnet or magnetic element must be disposed outside of the lens, which will increase the volume of the digital camera. Furthermore, since the current magnet or magnetic element is disposed around the coil, the direction of the magnetic line generated by the magnet or magnetic element is not perpendicular to that generated by the coil. Therefore, a larger current is required for the coil to generate a larger magnetic field for moving the lens or photoactive element. This will consume more electric power, which is unfavorable for the portable electronic device.
In order to overcome the drawbacks in the prior art, an improved digital camera module is provided. The particular design in the present invention not only solves the problems described above, but also is easy to be implemented. Thus, the present invention has the utility for the industry.